1. Field of the Invention
This invention relates to methods of producing slow release fertilizers made from urea and agricultural materials and slow release fertilizer compositions made according to the methods.
2. Description of the Prior Art
Grass turf and other cultivated plant crops are often grown using chemical fertilizers and pesticides. While these materials support a highly productive agricultural environment, the use of pesticides produces a soil environment substantially different from the natural soil ecosystem which has been characterized as a foodweb in which plant species evolved. Natural systems are characterized by a rich and diverse biomass activity with bacteria and fungi at the lowest level and predators such as protozoa, nematodes, earthworms, and higher level predators such as millipedes, centipedes, beetles, spiders and even small mammals . These organisms perform critical functions such as decomposing nutrients, retention of nutrients in the soil, symbiotic relationships involving transfer of nutrients into the roots, imparting immunity to disease, and controlling population of pathogenic organisms.
Prolonged use of pesticides has led to soil environments devoid of the natural bacterial and fungal activities and therefore also the larger predators in the foodweb. Pathogenic microorganisms gradually develop immunity to the pesticides and stronger and more potent chemicals are required. At the same time, these powerful chemicals are broad based toxins in themselves and are increasingly observed as pollutants in the air, soil and water and their use is increasingly regulated, restricted or prohibited.
There is a need for a soil additive which will promote the proper balance of microorganisms in the soil needed for healthy plant growth without or with minimal use of synthetic chemical pesticides. There is also a need for a method for systematically manipulating the activity of bacteria and fungi in soil to promote healthy plant growth.
Some applications of the use of alfalfa as a source of organic material are known. Prior to the availability and wide use of ammonia based fertilizers, alfalfa was been widely used for crop rotation, since as a legume it increased the nitrogen content of soil. Alfalfa is also known as a so-called xe2x80x9cgreen manurexe2x80x9d, a crop which is cut before it reaches full maturity and then incorporated back into the soil for soil improvement. Ground alfalfa meal and alfalfa pellets have been reported to have efficacy as a fertilizer for roses and irises. Alfalfa meal and pellets are often listed as one of a plethora of sources of organic matter for organic vegetable gardening. U.S. Pat. No. 4,767,440 discloses the use of pulverized wheat straw and alfalfa hay in substantially equal volumes as a potting medium to be used as a substitute for peat moss.
Alfalfa often has seeds of wild grasses and weeds incorporated with it which would present a problem if alfalfa would be used to fertlize a grass turf or in other large scale plantings where the wild grasses and weeds are objectionable. Also alfalfa meal or pellets do not quickly wet and incorporate into the soil, and can be blown by the wind or present an unpleasant appearance or interfere with golfers when placed on a grass golf turf
There is a need for an alfalfa composition which avoids the spreading of weeds, which can be readily applied, and which will quickly disintegrate and incorporate into the soil.
Organic soil additive compositions, such as those containing alfalfa, are best used with a high nitrogen fertilizer component. Many high nitrogen fertilizers are available such as ammonia, urea, and urea formaldehyde compositions, such as methylene urea as disclosed in U.S. Pat. No. 5,102,440, as well as other urea formaldehyde compositions. The advantage to the urea formaldehyde compositions are that they are characterized as being slow release compositions. Fast release high nitrogen fertilizers such as ammonia or urea are water soluble and as such are quickly released resulting in the fertilizer being washed away or producing xe2x80x9cbumxe2x80x9d on the plants, while slow release fertilizers avoid this problem. However, slow release urea formaldehyde fertilizers are substantially more expensive than fast release fertilzers such as urea or ammonia, hence the latter are still preferred.
There is a need for a new fertilizer formulation which renders urea into a slow release form when mixed with organic soil additives such as alfalfa containing soil additives.
My invention deals with a slow release fertilizer comprising agricultural materials, preferably including agricultural waste materials and urea. Preferred agricultural materials include alfalfa, other legumes, raisin stems, other fruit stems, rice bran, cotton seed, and nut shells such as walnut shells. I prefer that at least some of the components are high in tannins. Tannins are a phenolic component of plant materials which are concentrated in stems, stalks, and skins of plants. A particularly good source of tanins is raisin or generally grape skins.
I have found that alfalfa makes a particularly good soil additive for adding onto soil to promote growth of grasses and other plants. I have learned how to effectively use alfalfa by first pulverizing the alfalfa, then adding a wetting agent and the pelletizing the mixture of alfalfa and wetting agent so that the pellets can be conveniently applied but will quickly deteriorate when watered due to the interaction of the alfalfa with the wetting agent.
I prefer to use organic fertilizers, such as the above alfalfa fertilizer, in conjunction with a high nitrogen fertilizer such as urea. Urea is an excellent fertilizer for providing nitrogen for plant growth, however the nitrogen is made available to the plants too rapidly and urea tends to be quickly washed away because it is water soluble. Urea is made available to the plants by bacterial action which converts it to ammonia, which in turn is converted to nitrates which the plant can use as a nitrogen source for protein synthesis. When urea is placed out alone only a portion is actually utilized by the plant and the rest is washed away or evaporated. There is also a possibility of xe2x80x9cburningxe2x80x9d as is s well know problem in fertilization of grasses where too much nitrogen is made available to the plant in too short a time. In order to avoid this problem people have invented slow release forms of urea, in particular methylene urea and other urea formaldehyde reaction products such as are disclosed in U.S. Pat. No. 5,102,440. These formulations are characterized as having only a small fraction of soluble urea, and the rest is slowly converted to urea and ultimately nitrates by soil bacterial action. However, methylene urea or other urea formaldehyde components are very expensive compared to the other components, such as urea or ammonia fertilizers.
I have now discovered that if urea is mixed with agricultural materials such as alfalfa and raisin stems which have been pulverized and mixed with a surfactant, and that mixture of agricultural materials is heated in the presence of steam to an elevated temperature exceeding 170xc2x0 F., and then pelletized the pelletized feed has the desirable property that the urea is released slowly of a period weeks rather than quickly as would be expected had the materials not undergone the treatment as described above. The pellets readily disintegrate when exposed to water. The best results are obtained when the agricultural materials have been pulverized to about 16 Mesh, and the treatment time between ambient temperature and the elevated temperature is about 30 minutes.
I believe that the slow release properties are the result of a reaction between urea and tannins in the plant matter, or possibly proteins and carbohydrates which are complexed by the tannins.
It is an object of the invention to produce a high nitrogen slow release fertilizer containing agricultural materials and using urea as a nitrogen source.
The present invention includes several related soil additive compositions and methods for using them to promote healthy plant growth with minimal or more preferably without the use of pesticides. The elements of the invention cooperate to restore and maintain fungal and bacterial populations in the proper balance in the soil. These bacteria and fungi are themselves beneficial to plant health and growth, and are the lowest level of a food chain including predators such as protozoa, nematodes, earthworms, and higher level predators such as millipedes, centipedes, beetles, spiders and even small mammals which are also beneficial. These organisms perform critical functions such as decomposing nutrients, retaining nutrients in the soil, symbiotic relationships involving transfer of nutrients into the roots, imparting immunity to disease, and controlling population of pathogenic organisms. Bacteria, fungi, and the higher predators are typically depleted in soils which have been maintained with chemical fertilizers and pesticides. It is often necessary or desirable to reduce or eliminate the use pesticides. The present invention is useful in restoring the soil environment in such circumstances. Primary elements of the compositions include granular humate ore, alfalfa mixed with a synthetic wetting agent, and a calcium source which can include either calcium oxide or calcium carbonate.
The word humate is derived from the word humus which refers to organic residues in the soil which are products of the decomposition of plant matter. Humus is an important soil constituent for enhancing plant growth. Humic acid is the portion of soil humus that is soluble in alkaline solution but insoluble in acid solution. Humic acid is often added to soil to increase fertility. Humic acid is found in rotting vegetable matter, compost and manure. Humic acid is also be obtained from peats, manure, lignite, leonardite and low rank or even higher rank coals by chemical processes typically including extraction with caustic soda or biological processes. These materials from which humic acids are produced are frequently called humates.
In this invention, granular humate ore is used in a more limited sense, including potential sources of humic acids deriving from the decayed plant materials from ancient plant life which were deposited in the earth millions of years ago and were subject to biological and geological processes over time in the process which ultimately leads to the formation of coal. Granular humate ores include peats (a coal precursor which is characterized by having some free cellulose) and carbonaceous materials mined in the vicinity of peat deposits, low rank coals, naturally oxidized coals such as leonardite, and coals and artificially oxidized or treated coals from which humic acids can be produced. Materials such as compost, manures, and recently decayed plant or animal life are not included, nor are solutions of humic acids which have been produced and extracted from humus or granular humate ores.
Granular humate ore is a solid material which is substantially insoluble in water. If the material is a peat or peat like material it has typically been broken up and air dried in the sun. Granular humate ores are characterized by their cation exchange capacity, which is often expressed in the units of milliequivalents per 100 grams (meq. per 10 g.). Granular humate ores have cation exchange capacities between about 25 and about 600 meq. per 100 g. Beneficial results can be obtained over this entire range though the preferred sources are peat or materials mined around peat deposits having a cation exchange capacity over 300 meq. per 100 g and preferably between about 500 meq. per 100 g. and about 600 meq. per 100 g. A suitable granular humate ore is a material mined around a peat deposit having a cation exchange capacity of about 500 meq. per 100 g sold under the trade name HUMATE AG 1635 sold by Humate International, Inc.
Granular humate ore is the component of the invention which promotes primarily the growth of fungal mass in the soil. It will be discussed that it is desired to maintain a certain ratio of fungal mass to bacterial mass in the soil depending on the plant family. Granular humate ore is used rather than humic acids, composts, animal manures or the like because granular humate ore releases its organic materials in a slow and sustained manner, rather than quickly. Granular humate does not contain proteins, fats, or carbohydrates and is principally broken down and utilized by fungi. I have found that the beak down of granular humate is greatly facilitated by a calcium source which should be co-present with the granular humate ore. The calcium source should include either calcium carbonate or calcium oxide. Calcium is also a plant nutrient and can be used for soil pH control and may be administered at different times during the year, however for the best operation of this invention it is important to apply the calcium contemporaneously with the granular humate ore. I have found that other forms of calcium such as calcium sulfate are not acceptable substitutes for calcium carbonate or calcium oxide. Calcium carbonate is the preferred form.
Alfalfa for this invention should be pulverized to a size which will pass through a 48 mesh screen and preferably a 100 mesh screen. The size is important because alfalfa will contain seeds from weeds and wild grasses which will contaminate the soil. Pulverizing the alfalfa destroys these seeds. This is particularly important if the compositions will be applied on grass. Alfalfa normally contains a variety of microbes and notably cyanobacteria. It is preferred that the alfalfa be treated in a manner which leaves a population of cyanobacteria remaining after pulverizing. Cyanobacteria are killed at temperatures in the range of 165xc2x0 F. to about 185xc2x0 F. so it is preferred that the alfalfa not be exposed to a temperature above 185xc2x0 F. and preferably not above 165xc2x0 F.
When alfalfa is applied alone to soil it does not quickly break down and deteriorate. This is particularly true when the pulverized alfalfa is formed into small pellets, extrudates or granules which are typically from about {fraction (1/16)}th of an inch in diameter to xc2xc inch in diameter and xc2xd inch to an inch long. Such pellets are a convenient way to handle and distribute the alfalfa without excessive wind losses and are a preferred form of the product. Pellets, extrudates, and granules may be formed in any of a variety of conventional equipment used for that purpose in industry. A preferred device is a pellet mill. Rapid break down of the alfalfa is important to make it available to soil bacteria. In the case where the invention is used on grass covered soil of a lawn or golf course the presence of the alfalfa pellets is detrimental to the appearance and interferes with golfing making alfalfa alone generally unsuited for such applications. If the alfalfa is not pelletized, there is excessive wind loss. I have found that the addition of the wetting agent to the alfalfa makes the alfalfa deteriorate rapidly, usually within a few hours, while a much longer period would be required without the wetting agent. Preferred wetting agents are in the class of nonionic wetting agents, though other wetting agents such as anionic, cationic or ampholytic agents may also be used. A preferred way to apply the wetting agent is to mix a liquid wetting agent with the pulverized alfalfa such that the wetting agent is absorbed by the alfalfa. The amount of wetting agent is between about 0.25 gallons per ton and 2.5 gallons per ton of alfalfa, and more preferably between 0.5 and 1.5 gallons per ton of alfalfa. Since the wetting agents are an expensive component, I prefer to use as little as possible while getting a rapid enough deterioration of the alfalfa. A preferred nonionic wetting agent is sold under the trade name AQUA-AID manufactured by Aqua-Aid, Inc. and contains alkyl ethoxylates, dodecyl benzene sulfonates, and oleic diethanolamides.
In order for the alfalfa to be efficiently used by bacteria it is desirable to lower the carbon to nitrogen weight ratio from 12 or 13 to 1 found in alfalfa to a value below 10. This allows the alfalfa to be consumed by the microbes, principally bacteria, and become incorporated in the microbial mass which will ultimately be consumed by predators and converted into a form useable by the plants. I prefer to mix the alfalfa and wetting agent with one or more high nitrogen fertilizers for this purpose. Suitable fertilizers for mixing include urea; urea formaldehyde products such as urea formaldehyde, polymethylene urea, methylene urea, methylene diurea; triazone and substituted triazones; isobutylene diurea; monomethylol urea; crotonylidine diurea; diammonium and monoammonium phosphates; urea phosphate; ammonium nitrate; ammonium sulfate; animal blood; tankage; and cotton seed. Tankage is a byproduct of animal slaughtering made up of meat scraps, bone, and blood.
Calcium nitrate and or potassium nitrate may be optionally added. These compounds do not promote bacterial growth but are a form of nitrogen readily used by the plants without microbial action. Such compounds are often desired because some time is required for the degradation products from the alfalfa and high nitrogen fertilizers to be available to the plants.
I prefer to limit the addition of total soluble phosphates, such as ammonium phosphates used as sources of high nitrogen content and other soluble phosphates such as potassium phosphate which may be added for phosphate content, when expressed as P2O5 to less than 2%, preferably less than 1%, and most preferably about xc2xd% of the total mixture. The reason for this is that in the natural microbial system promoted by my invention, phosphorus is transferred to the plants from insoluble sources through the symbiotic associations of fungi and plant roots known as mycorrhizae. These associations are reduced or absent in soil which has been fumigated with fungicides and in such systems without sufficient microbial presence it is necessary to supply phosphorus in a water soluble form which be taken up directly by the roots. The mycorrhizae do not thrive and remain attached to the roots if there is too much soluble phosphate available. Mycorrhizal activity is measured as a percentage of root coverage, which can be measured in the laboratory by well known procedures.
A preferred mixture includes alfalfa, wetting agent, with nitrogen fertilizer components added to bring the nitrogen content between about 6% and about 15%, more preferably between 6% and 10%.
The alfalfa and wetting agent are preferably mixed with the high nitrogen fertilizers and optional nitrate additives. The mixture can be applied in fine pulverized form or preferably manufactured into pellets, extrudates, granules or other agglomerates. Pellets, extrudates, and granules may be formed in any of a variety of conventional equipment used for that purpose in industry. A preferred device is the device commonly referred to as a pellet mill, where the material is forced through openings in a drum rotating around one or more internal rollers. Other devices such as a compacting mill are also suitable as are the many devices and methods for size enlargement described in pages 8-60 to 8-72 of Perry""s Chemical Engineer""s Handbook, Sixth Edition, McGraw-Hill, 1984, which is hereby incorporated herein by reference. The purpose of size enlargement is convenience of application and to prevent wind loss. Binders and lubricants may be used. When a pellet mill is used a preferred lubricant is rice hulls.
The alfalfa and additives mixture may be applied alone or combined with the granular humate ore and calcium components. A preferred annual program includes some applications where all the components are applied together and other separate additional applications of alfalfa, wetting agent , high nitrogen fertilizer, and optional nitrates, and other applications of only calcium. For the best results of this invention, alfalfa, wetting agent, and high nitrogen fertilizers are added together and calcium is added with granular humate ore. It is preferable to combine the ingredients where possible because their mutual interaction is beneficial, and to reduce the additional costs of separate applications.
When a grass is the plant being grown, it is desirable to add the combined applications and humatexe2x80x94calcium applications so that as much as possible of the materials are applied within the thatch zone, preferably at least 50%. Thatch is a collection of trimmings and fallen plant materials which accumulates at the soil surface. Thatch accumulation is a problem because it impedes the flow water into the soil. The ingredients of this invention promote the growth of microbial species which quickly decompose the thatch and recycle its ingredients to the soil foodweb in a manner ultimately useable by the grass. A convenient way to make the applications is to apply the soil additives of this invention immediately following aerification. Aerification is a process where small holes are mechanically made in the soil to incorporate air. When the ingredients are applied after aerifacation they fall into the holes. It is preferable to drag over the soil with large mats after application to further fill the aerification holes with the additive ingredients.